NFPA Hazard Rating: Reactivity (Yellow)

4

Materials which in themselves are readily capable of detonation or of explosive decomposition or explosive reaction at normal temperatures and pressures.

This degree should include materials which are sensitive to mechanical or localized thermal shock at normal temperatures and pressures.

3

Materials which in themselves are capable of detonation or of explosive reaction but which require a strong initiating source or which must be heated under confinement before initiation.

This degree should include materials which are sensitive to thermal or mechanical shock at elevated temperatures and pressures or which react explosively with water without requiring heat or confinement.

2

Materials which in themselves are normally unstable and readily undergo violent chemical change but do not detonate.

This degree should include materials which can undergo chemical change with rapid release of energy at normal temperatures and pressures or which can undergo violent chemical change at elevated temperatures and pressures. It should also include those materials which may react violently with water or which may form potentially explosive mixtures with water.

1

Materials which in themselves are normally stable, but which can become unstable at elevated temperatures and pressures or which may react with water with some release of energy but not violently

0

Materials which in themselves are normally stable, even under fire exposure conditions, and which are not reactive with water.